This invention relates to an improved locknut and more particularly to a locknut having thread convolutions which are formed by making indentations in the body of the locknut.
The concept of forming lock thread convolutions by making indentations in the body of a nut is disclosed in U.S. Pat. No. 3,456,704. In this patent the indentations are relatively large. Thus, the indentations in this known nut have a height which is substantially greater than half of the height of the wrenching flats on the nut. In addition, the indentations have a width which is substantially greater than half of the width of the wrenching flats on the nut.
The relatively large indentations on the nut shown in U.S. Pat. No. 3,456,704 tend to reduce the number of free running standard thread convolutions which can be provided on the nut and promotes abrading of external thread convolutions when the nut is turned onto an externally threaded member. In addition, a relatively high degree of friction may develop between the lock thread convolutions and the externally threaded member. This friction tends to reduce the number of times which the nut can be reused with a suitable locking action.
Other locknuts having indentations to form locking thread convolutions are disclosed in U.S. Pat. Nos. 1,903,921 and 3,678,978. Although the indentations shown in these locknuts are smaller than the indentations utilized in the locknut shown in the aforementioned U.S. Pat. No. 3,456,704, the indentations provided in the locknuts disclosed in these two patents have a generally rectangular configuration and are sharply indented into the side of the lockout. There is also a relatively large deformation of the lock thread convolutions and a relatively large degree of friction between the locking thread convolutions and the standard thread convolutions on an externally threaded member. Although the relatively high degree of friction does provide a substantial initial locking action, the greater the degree of friction the fewer times the nut can provide a suitable locking action without abrading the mating threads on a bolt.